--> Abstract: Spatial and Temporal Controls on the Development of Southern North Sea Delta Systems during the Late Tertiary and Quaternary, by C. J. Kay; #90987 (1993).

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KAY, CHRISTINE J., The University of Edinburgh, Grant Institute, Scotland, UK

ABSTRACT: Spatial and Temporal Controls on the Development of Southern North Sea Delta Systems during the Late Tertiary and Quaternary

The Late Tertiary and Quaternary of the Southern North Sea basin was characterised by high subsidence and sedimentation rates, as well as fluctuations in eustatic sea levels. Basin margin uplift led to loading of the north-west European rivers with large quantities of freshly weathered detritus. The result was the formation of a large delta system which laterally occupied most of the southern North Sea area, and reached thicknesses in excess of 1700 m in the Central Graben region.

The morphology and growth history of this delta system has been reconstructed using a grid of speculative seismic lines shot and processed by NOPEC. Twenty eight regional event horizons, thought to relate to changes in relative sea level, have been identified and mapped using the Zycor mapping package.

Palaeosurface maps have been compared with isopach maps to reconstruct morphology, growth patterns, and depositional styles at each stage. Six orders of trend surface maps along with their residuals allow the influence of underlying structures to be examined at both a regional and local scale. Together, these maps indicate that depositional patterns were controlled by a complex interaction of basin margin uplift, changing source areas, waning tidal influence and increasing dominance of sediment input, late stage increases in subsidence rate, and fluctuations in the eustatic sea level. The delta is reconstructed on a sequence by sequence basis, allowing the changing influence of controlling factors to be assessed throughout the lifespan of the delta system.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.